Concentration of minerals



June 14, 1938. E. w. WILKINSON CONCENTRATION OF MINERALS 2 Sheets-Shee t. 1

Filed Dec. 21, 1936 o'- 14 11 .4 13 in (Jn------.-..

I IIHHIHHHHHHHHHHH \YEA W l 18 INVENTOR.

Patented June 14, 1938 UNITED STATES CONCENTRATION OF MINERALS Eltoi't Wray Wilkinson, Berkeley, Calii'., assignor to Minerals Separation North American Corporation, New York, N. Y., a

Maryland corporation of This invention relates to the concentration of non-sulphide minerals. It has been found to be particularly useful in the concentration of phosphate-bearing material, but it is not to be regarded as limited in usefulness to that material, since it is also usefully applicable to the following -minerals: Cassiterite, copper carbonate, beauxite. manganese oxide, iron oxide, barytes, lead carbonate, zinc carbonate and zinc silicate, as 'is true of the process described and claimed in United States Letters Patent to George Albert Chapman and John W. Littleford, No. 1,968,008, issued July 24, 1934.

The invention may be regarded as an improvement upon the process described and claimed in the aforesaid Letters Patent to George Albert Chapman and John W. Littleford. As explained in that patent, when the process of that patent is employed for concentration of phosphate-bear- 20 ing material; with the use of a shaking table,

many phosphate particles float on the water surface as a skin or him float and are carried oif into the concentrates launder by the stream of water flowing transversely across the table; and other phosphate particles, many of them in flocks associated with air bubbles, form aggregates or loosely bonded agglomerates and, in suspension in the water, or resting lightly on the silica-or other impurities, are carried transversely across the table into the concentrates launder by the transversely flowing stream of water; while the silica or other impurities settle on the table between the riflies and, owing to the endwise movement of the table, pass ofi the table at-or near the end thereof.

The present invention is the result of the discovery that if a mineral pulp, which has been suitably conditioned with agents promoting the formation of skin-floated particles and loosely bonded agglomerates of particles, for example in the manner described in the aforesaid Chapman & Littleford patent, is aerated by passing air upwardly through it during its treatment upon a shaking table or equivalent apparatus, then the production of the skin or film float and of the loosely bonded agglomerates is greatly facilitated, with the result that a greatly increased amount of material to be treated may be fed to the. shaking-table or equivalent apparatus per to saying that the amount of. material which may be treated in a given time, upon a table or equiv- 5a alent apparatus having a given area, may be greatly increased by the use of the present invention.

While each of the forms of the apparatus hereinafter described for practicing the present invention is essentially a shaking table provided with a porous deck through which air passes upwardly into the pulp and water flowing across it,

7 it is to be understood that the invention may be sectional plan view of said deck on the line 3-3 of Fig. 2; Fig. 4 is a sectional elevation of said deck on the line 4-4 of Fig. 3; Fig. 5 is a plan view of another kind of shaking table deck which may be used in practicing the invention; Fig. 6 is a sectional elevation of said deck on the line 6--6 of Fig. 5; Fig. 7 is a sectional plan view of said deck on the line 1-1 of Fig. 6; and Fig. 8 is a sectional elevation of said deck on the line 8-8 of Fig. 5. Like parts are referred to throughout the drawings by the same or similar reference characters.

It will be understood that the table decks illustrated in the drawings are supported so as to permit adjustment of their transverse inclination,

.and are recip'rocated longitudinally, by any well known means, which it is unnecessary to illustrate.

Referring first to Figs. 1 to 4, the bottom or base portion of the deck, shown at I0, may be made of wood or other suitable material. In the top of the base ID are channels Ii, the formand arrangement of which are shown in Figs. 2, 3 and 4. These channels may be cut or otherwise formed in the base III, or may be formed by ribs I secured to the base. Stretched over and secured to the base Mover the channels II, is a porous medium such as a sheet of canvas ii. on the top of the canvas l3 and secured thereto, preferably on top of the ribs beneath it, are riilles ll. In order that the air which is fed under pressure to the channels ll beneath the porous medium l3 maybe suitably controlled, the channels II are divided into groups 'or zones to each of which the compressed air may be separately fed. The groups or zones into which the table deck is thus divided are bounded by the dot-and-dash lines in Fig. 3; and, for convenience of reference, the various zones are lettered A, B, C and D. It will be apparent from Figs. 2, 8 and 4 that air entering the pipe l5, leading to one of the channels H in zone A, can pass from that channel into the other channels in that zone through openings ll in the bottoms of the ribs thereof; that the air entering zone B, through the pipe I1, is free to pass from the channel Ii with which that pipe I! connects to the other channels in that zone, through the openings It in the bottoms of the ribs in that zone; that the airentering zone C through the pipe I8 is free to pass from the channel M with which that pipe I! connects to the other channels in that zone, through the openings in the bottoms of the ribs of that zone; and that the air from the pipe 2 I, communicating with one of the channels I i of zone D, is free to pass from that channel into the other channels of that zone, through the openings 22 at the bottoms of the ribs of that zone. The usual feed box is indicated at 24; and the usual water-distributing box is indicated at 2!. Along the lower side of the table deck is the concentrates launder 21; and along the end of the table deck is the tailings launder 28. The table deck illustrated in Figs. 5 to 8 differs from the table deck shown in Figs. 1 to 4 principally in the fact that it is divided into three zones E, F and G arranged diflerently from the zones A, B, C and D of the table deck shown in Figs. 1 to 4. Referring to Figs. 5 to 8, the bottom or base portion of the deck is shown as composed of shallow metal boxes or trays 30, 3| and 32 having the shape of the zones E, F and G, as best shown in Fig. 7. One side-of the box. is secured to one side of the'box 3| by bolts 35; and the other side of the box F is secured to one side of the box G by the bolts 38. Secured within.the boxes 30, 3| and 32, as best shown in Fig.

'7, are ribs 38, 39, 40, ll, 42, 43 and 44 having the same height as the sides of the boxes. These ribs are provided with openings 45 so as to permit the free passage of air through them. The tops of each of the boxes 30, 3| and 32 are covered by a porous medium such as sheets of canvas 41, 48 and 49, the edges of which are secured to the walls of the boxes in any suitable manner. 0n the top of the canvas sheets, and secured thereto and to the ribs 38 to 42, are rifiies Sli. A preferred arrangement of the riffles 50 is shown in Fig. 5, but it will be understood that other arrangements of riilles may be used. Compressed air may be fed to the boxes 30, 3| and- 32, of the zonesE, F and G, through pipes N, and 56. The usual feed box is indicated at C0; and the usual water-distributing box is indicated at 6|. The concentrates launder 64 extends along the lower side of the table deck; and the tailings launder 65 extends along the end of the table deck.

The rifles II (in the form of table top shown in Figs. 1 to 4) and the riiiles 50 (in the form of table top shown in Figs. 5 to-8) are considerably higher than the riflles used on ordinary shaking tables employed for practicing the .process of the aforesaid Chapman and Littleford patent.

Each riiile decreases in height from the feed end of the table toward the delivery end thereof, as

mahown in Figs. 2 and 6. Moreover, said rillles preferably increase in height from the upper or feed side to the lower or delivery side of the table.

deck, as is shown in Figs. 4 and 8. Rimes having a maximum heightof of an inch at the 7 feed end of the table and a minimum height of of an inch at the other end, have been found to give satisfactory results in treating a Florida phosphate feed prepared by screening through a 14-mesh screen.

In practicing the present invention, it has been found desirable to incline the table toward the delivery side thereof considerably more than when practicing the process of the aforesaid Chapman and Littleford patent with ordinary shaking tables. For example, an inclination from the horizontal approximately of 8 to 10 has been found to give satisfactory results. It will be understood, of course,'that the inclination of the table should be adjusted by the operator so as to give the best results, according to his observations.

It will be understood that the conditioned feed. usually with additional water, is fed to the feed box from which it flows on to the table; and that water is fed to the distributing box from which.

it flows on to the table in the usual way. Compressed air is fedto the zones of the table, under the control of the operator who will regulate the supply of air so as to produce the most useful aeration of thepulp. It will, of course, be understood that it may not be necessary or desirable to supply compressed air to all of the zones of the table. When the process is carried out with the form of table top shown in Figs. 1 to 4, it will be found thatthe advantage resulting from the aeration of the pulp decreases from zones A to D; and with the form of table top shown in Figs. 5 to 8, that the advantage arising from aeration of the pulp decreases from zones E to G. As the supply of air to each of the zones is controllable, the operator can regulate the aeration of the pulp in the way be finds most advantageous, and can even shut off the supply of air entirely to one or more of the zones. 1

In practicing the present invention, the m,- terial to be concentrated is, of course, made amenable to the process by conditioning it with any suitable selective agentspromoting the forfmation of skin-floated particles and loosely bonded agglomerates of particles, such as, for example, soap (made separately or in situ from fatty acids and caustic soda) and fuel oil, as described in the aforesaid Chapman andLittleford patent.

In practicing the process which is the present invention, the separation of the mineral values from the gangue takes place in the manner hereinbefore described in referring to the Chapman and Littleford patent, except that, due to the aeration of the pulp by the air passing up through it, the production of the skin or film float and of the loosely bonded agglomerates is greatly facilitated. For this reason, it is possible to treat by this process, with satisfactory results so far as the grade and the recovery of the phosphate or other mineral values are concerned, a greatly increased amount of material in a given time upon a table or equivalent apparatus having a given area.

I claim:

1. The method of concentrating a non-sulphide material containing valuable and gangue particles, which consists in conditioning the said material with selective flocculating agentspromoting the formation of skin-floated particles and loosely bonded agglomerates of particles, then flowing a pulp of said conditioned material in a thin layer over a porous moving surface through which air is passing upwardly, thereby facilitating the creation on and in the pulp of skin-floated particles of one kind and loosely bonded agglomerates of particles of the same kind, and together delivering and collecting the said skin-floated particles and the said loosely bonded agglomerates from said surface separately from the other particles.

2. The method of concentrating a non-sulphide material containing valuable and gangue particles, which consists in conditioning the said material with selective flocculatlng agents promoting the formation of skin-floated particles and loosely bonded agglome'rates of particles, then flowing a pulp of said conditioned material in a ,thin layer over a riflled, porous, inclined moving surface through which air is passing upwardly, thereby facilitating the creation on and in the pulp of skin-floated particles of one kind and loosely bonde'd agglomerates of particles of the same kind, and together delivering and collecting the said skin-floated particles and the said loosely bonded agglomerates from said surface separately from the other particles.

EL'IOFTWRAY WILKINSON. 

